In recent years, researches have been actively made into a light-emitting device which uses, as illumination light, fluorescence that a light-emitting section containing a fluorescent body generates in response to excitation light emitted from an excitation light source which is a semiconductor light emitting element such as a light emitting diode (LED) or a semiconductor laser (LD: Laser Diode).
A technique related to such a light-emitting device is exemplified by light-emitting devices disclosed in Patent Literatures 1 through 4.
Patent Literature 1 allows a vehicle headlamp having variable illumination characteristics to be mechanically simply structured and improves obstacle resistance and response speed. Patent Literature 2 discloses a headlight which, while restraining an enlargement, is capable of (i) reducing electric power consumption and (ii) forming desired density in a light distribution pattern. Patent Literature 3 discloses a vehicle lamp capable of electrically switching between a horizontally wide light distribution pattern and a light distribution pattern suitable for AFS (Adaptive Front-lighting System) casting light beams leftward and rightward. Patent Literature 4 discloses a light source device which prevents a device from getting large-sized, increasing in weight, and getting high in manufacturing cost even in the light source device equipped with a function of varying light distribution.